Pneumatically-activated control valves are of course well-known in the art, and such valves have also been known in the art for their use in connection with the controlled discharge of various materials, including, for example, the controlled discharge of hot melt adhesive materials to an applicator device or nozzle. An exemplary, well-known pneumatically-activated control valve, having the product designation MR1300 and manufactured by ITW DYNATEC of Hendersonville, Tenn., is illustrated in FIG. 1. For background purposes, the illustrated valve assembly will not be described in exhaustive detail, but will only be described in sufficient detail in order to provide a sufficient understanding of the major components of the valve assembly and the operation thereof.
More particularly, the valve assembly is generally indicated by the reference character 10 and is seen to comprise a module body 12 which has mounted within the lower end portion thereof a nozzle adapter and valve seat assembly 14. A piston assembly, comprising a piston valve stem 16, which passes through a seal cartridge 18 such that the lower end of the piston valve stem 16 operatively cooperates with the valve seat of the assembly 14 so as to selectively control the discharge of adhesive material from the valve assembly 10 during adhesive application cycles, and a piston head 20 swaged to the upper end of the piston valve stem 16, is vertically movable within the valve assembly 10 so as to achieve the OPEN and CLOSED states of the valve assembly 10 as desired for adhesive application cycles.
An air cylinder 22 is bolted to the upper end of the module body 12 by means of a plurality of threaded bolt fasteners 24, and an O-ring 26 is mounted within a sidewall portion of air cylinder 22 so as to be disposed around an air inlet passage, not shown, through which pneumatic air is transmitted so as to act upon the upper surface of piston head 20 when it is desired to move the piston assembly vertically downwardly in order to move the lower end of the piston valve stem 16 from its OPENED position to its CLOSED position with respect to the valve seat of the nozzle adapter and valve seat assembly 14 so as to terminate the discharge of adhesive material from the valve assembly 10. A stop member 28 is coaxially mounted within the upper end of the air cylinder 22, and secured therein by means of a hex nut 30, so as to limit the upward movement of the piston assembly, and a pair of inner and outer coil springs 32,34 are respectively disposed about the lower end of the stop member 28 and engage the upper surface of the piston head 20 so as to tend to bias the piston assembly downwardly whereby the piston valve stem 16 is effectively biased toward its CLOSED position.
The upper end of the module body 12 is provided with a recessed or counterbored seat 36 and an axial passageway 38 for accommodating the seal cartridge 18, a seal cartridge gasket being illustrated at 40. Another O-ring member 42 is adapted to be mounted upon an upper sidewall portion of the module body 12 so as to be disposed around an air inlet passage, not shown, through which pneumatic air is transmitted so as to act upon the undersurface of piston head 20 and thereby cause vertically upward movement of the piston assembly, and the consequent lifting of the lower end portion of the piston valve stem 16 with respect to the valve seat of the nozzle adapter and valve seat assembly 14, from its CLOSED position to its OPENED position, when it is desired to discharge adhesive material from the valve assembly 10. A third O-ring member 44 is adapted to be mounted upon a lower sidewall portion of the module body 12 so as to be disposed around an adhesive material inlet passage, also not shown, through which the supply of adhesive material is transmitted to the valve assembly 10.
While the aforenoted valve assembly 10 is of course quite satisfactory from an operational point of view, and has enjoyed and exhibited substantial commercial success, there are manufacturing processes and production assembly lines which utilize adhesive material valve applicators or assemblies similar to the valve assembly 10 but which require an adhesive material production output, discharge, or flow-through, per unit of time, which is greater than that able to be produced by means of a valve assembly such as the valve assembly 10 illustrated in FIG. 1 or similar thereto.
Accordingly, in order to achieve such a desired increased or enhanced adhesive material output, several options are possible and have been suggested, however, for one or more reasons, none of such options have proven or seem to be viable. For example, a first proposed option would be to utilize a larger valve assembly, however, larger valve assemblies are slower in operation thereby presenting problems in connection with the satisfaction of production line requirements, and in addition, the larger valve assembly, by definition, as a result of being larger, would not in effect be able to fit or be accommodated within the footprint of the existing valve assemblies whereby the newer valve assemblies would not be able to be retrofitted upon existing valve heads or modules.
A second alternatively proposed option would be to utilize a larger number of valve assemblies or modules in order to increase the adhesive material output as required, however, hot melt adhesive valve assemblies or modules require a predetermined amount of periodic maintenance. It is therefore desirable from a production point of view, as well as from a cost-effective point of view, to operationally limit the number of valve assemblies or modules in order to accordingly limit the amount of maintenance required in connection with the serviceability of the various valve assemblies or modules comprising a particular production line or arrangement, and the costs involved in maintaining the production line or arrangement in service without significant downtime.
A need therefore exists in the art for a new and improved high-flow pneumatically-controlled, hot melt adhesive applicator valve assembly which is able to discharge or dispense substantially large quantities of hot melt adhesive material, which exhibits relatively high-speed OPEN and CLOSE operational cycles so as to accurately achieve the discharge or dispensing operations as desired and when required despite the enhanced amount of hot melt adhesive material being discharged or dispensed, and which is substantially the same size as the known or prior art valve assemblies such that the new and improved high-flow pneumatically-controlled, hot melt adhesive applicator valve assemblies have substantially the same footprints as those of the known or prior art valve assemblies whereby the new and improved high-flow pneumatically-controlled, hot melt adhesive applicator valve assemblies can be retrofitted upon existing pneumatically-controlled, hot melt adhesive applicator valve assembly equipment.